McLaren Vale - Botrytis increasing but some hope of a good harvest if fruit handled with care - UPDATE 23/3/2011
We have spent the last two days in and out of vineyards in McLaren Vale. We are worried, but consider ourselves quite fortunate. Considering what is being reported from vineyards in Langhorne Creek, Currency Creek, Adelaide Hills we are grateful in McLaren Vale for our luck with the weather.
Where Chardonnay, Sauv Blanc etc have already been harvested, they have come off in good condition. What white varieties that remain unpicked are now developing high levels of botrytis bunch rot and are unlikely to be suitable for making table wine if they are not picked immediately.
Cabernet Sauvignon is still in good condition and could hold together the 7-14 days needed to develop full ripeness.
Viognier, Sangiovese, Tempranillo, Grenache have varying amounts of bunch rot. Some sites are in quite good condition at the moment, especially where canopies are open and/or good flowering and prebunch botrytis treatments were applied, other sites have 10-20% infections and are likely to be downgraded or not suitable for winemaking.
McLaren Vale's A & B grade Shiraz will be mostly harvested by middle of next week and is still in good condition with less than 1% bunch bot. A & B grade fruit would account for around 20-30% of the district.
The better C grade Shiraz vineayrds are also holding with only 1-5 single berries of bunch infection per panel, ie less than 1%. These vineyards are sitting around 12.5 – 13.5 baume and many will be harvested by the end of next week.
All up this would see around 70-80% of the Shiraz crop harvested in good condition.
Areas of heavier canopy and where canopy manipulation, irrigation management has been poor we do have some Shiraz crops in trouble, with continued rain today, we may lose 5-10% of the Shiraz crop.
We are hopeful that a good harvest can still occur if the weather clears. The majority of the botrytis we are seeing has come from single berries with latent infection.
If we get dry weather we would expect these berries/bunches to shrivel and fall off.
We are on the edge at present - and hope for dry conditions.
Derek Cameron & James Hook
Proprietors/Senior Horticultural Consultants